An electric vehicle typically includes energy storage systems that store electrical energy, such as battery packs. Power circuitry within the electric vehicle uses energy stored in the battery packs to drive an electric motor of the electric vehicle. After the energy stored in the battery packs has been depleted, the battery packs must be charged. An electric vehicle charge station couples the power circuitry of the electric vehicle to an Alternating Current (AC) power source to charge the battery packs.
Electric vehicle charging stations usually must comply with safety regulations and standards because of the hazardous voltage and current levels available at the AC power source to the power circuitry of the electric vehicle. UL 2231 defines standards for electric vehicle charging stations and for protection devices in the charging stations. One type of protection device commonly found in a charging station is a Ground Fault Interrupter (GFI) circuit. If the GFI circuit detects imbalanced current on the charging conductors, then the GFI circuit disables the charging station and the electric vehicle battery packs stop charging. This requirement limits the common mode capacitance of vehicle circuits to a low value, which can be difficult to achieve for some vehicle designs.